The Center of Curvature is the geometric center of the sphere from which the concave mirror was cut. It is always a point in front of the Focus Point, which is a midway point between the Center of Curvature and the middle of the mirror. The Principal Axis is a line drawn from the Center of Curvature, through the Focus Point, to the middle of the mirror, which is known as the Vertex.
If an object is placed just outside the Focus Point, it will be between the Focus Point and the Center of Curvature. Such placement of an object would create an image that is out past the Center of Curvature, but is real, inverted, and larger than the object. If it is moved further away from the Focus Point and closer to the Center of Curvature, the resulting image will remain real and inverted, but will become smaller. As it reaches the Center of Curvature, the resulting image will be the same size as the object. Moving the object beyond the Center of Curvature will result in an image being formed real and inverted, but smaller still and closer to the Focus Point.